Low birth weight (LBW) is defined by the World Health Organization as a birth weight of an infant of 2,499 g (5 lb 8.1 oz) or less, regardless of gestational age. Infants born with LBW have added health risks which require close management, often in a neonatal intensive care unit (NICU). They are also at increased risk for long-term health conditions which require follow-up over time.